Weird Electrical Issue (1 Viewer)

[CruiseCruise]

Hey everyone, so a few weeks back I had a shop replace my motor mounts and everything went smoothly even after picking it up and driving it back home, no issues. A few days later I turned on the car and it threw a CEL and after scanning it it was a p0120 and so after inspecting the TPS sensor I found one of the wires had disconnected and ripped off from the connector. No problem, I ordered a new pigtail connector from eBay and it arrived and so I used butt connectors to crimp the wires in the correct positions and then connected it back to the TPS. I turned on the vehicle and it fired right up and no CEL was present, possibly because I had disconnected the battery cables so I could do the rewiring job. So I decided to take the car for a drive and make sure everything was fine and as soon as I pulled out of the driveway in reverse, I shifted into Drive and as soon as I gave the pedal some throttle, the vehicle completely lost power and shut down. Fortunately I was able to steer it towards the curb where I put into park and let it rest. I had no power whatsoever and it had never done this before. About a minute later, the power came back immediately and I was able to crank it over again and this time I was also able to drive it and which I did for about 7 miles and everything was great. Fast forward to this week during the LA wildfires, I got a notice to evacuate and of course I was going to take the Land Cruiser which I packed with a few of my belongings I was able to take. Thankfully our area did not get hit by the fires but it was definitely close. Again when I started the car it immediately died after putting into drive from reverse. Again I pulled it over the curb and this time the power did not come back, it just completely died and so I left it there and took my other car. When everything was safe and we were cleared to return I came back home and tried to start it back up and it wouldn't unless I used a battery jumper. I brought it back into the driveway, inspected the battery and realized it had bloated and after getting it checked at auto zone it failed so I took it to costco and got a new battery. After installing the new battery I started the car back up and it still had some weird electrical issues almost like there wasn't enough power even though my alternator voltage is showing normal signs. After I started the car with the new battery it started to stumble and the RPM's kept dropping. I checked all the connections and everything seemed to be in order. So i decided to disconnect the TPS sensor and the CEL came back on but this time it was performing better and wasn't stumbling and dropping in RPM's but it wasn't great. Then I connected the sensor again and cleared the code and it started to work normally and the RPM's were between 640-680 and it drove normally. I can't understand what could've happened. I'm not sure if my wiring job caused my battery to go bad or if the pigtail connector was faulty but for some odd reason I had an electrical issue that was causing all sorts of problems that fixed itself in the end and I'm not sure if it is even fixed. I'm so confused, any help or input would be appreciated.

 

[jonheld]

because I had disconnected the battery cables so I could do the rewiring job.

Right there is the first thing to look at, next would be fusible links off the positive battery terminal.

 

[CruiseCruise]

Right there is the first thing to look at, next would be fusible links off the positive battery terminal.

I checked there too, and everything looked fine including the fusible link but only from what I could see. Could there be a portion of the fusible link that's hidden inside of the junction box that could be damaged? My concern is if that is the issue, would it cause my battery to go bad? My battery was pretty old btw but it just seems coincidental that all of these happened at the same time.

 

[60 toy ota]

Most issues with the fusible links can't be seen. Double check that you wired the Tps correctly. Finally, I wouldn't use those cheap plastic lined butt connectors on a derby car. If you don't have the means to do an oem style crimp then I would solder it if I were you. I'd put good money those crimps are causing issues for you

 

[CruiseCruise]

Most issues with the fusible links can't be seen. Double check that you wired the Tps correctly. Finally, I wouldn't use those cheap plastic lined butt connectors on a derby car. If you don't have the means to do an oem style crimp then I would solder it if I were you. I'd put good money those crimps are causing issues for you

That was the first thing I checked, I matched the correct wires to the correct terminals on the pigtail and crimped them together. I will mention that this was the first time I crimped any wires ever and I was fairly confident I did a good job but now i'm starting to second guess myself. Is it possible that a faulty wiring job could cause damage to my battery??

 

[jonheld]

I checked there too, and everything looked fine including the fusible link but only from what I could see. Could there be a portion of the fusible link that's hidden inside of the junction box that could be damaged? My concern is if that is the issue, would it cause my battery to go bad? My battery was pretty old btw but it just seems coincidental that all of these happened at the same time.

Fusible links have a flameproof silicone jacket. You can not determine the condition with your eyeballs. They are prone to failure due to vibration and IMO should be replaced with every battery change. Since you disconnected the battery and now you said you've lost all power, my first thought is a battery clamp or the associated wires are loose or damaged.
That would be the low hanging fruit.

 

[BTLSHP]

Fusible links have a flameproof silicone jacket. You can not determine the condition with your eyeballs. They are prone to failure due to vibration and IMO should be replaced with every battery change. Since you disconnected the battery and now you said you've lost all power, my first thought is a battery clamp or the associated wires are loose or damaged.
That would be the low hanging fruit.

Holy cow, we have never given ours a second thought in a 30 year old vehicle. I think it is time to buy a spare for the glove box before we hand it off to my daughter.

 

[jonheld]

Holy cow, we have never given ours a second thought in a 30 year old vehicle. I think it is time to buy a spare for the glove box before we hand it off to my daughter.

Yea, it's one of those items folks don't think about. I always keep a new spare in the truck and the existing one is strain relieved.
90982-08264 about $15-$20 depending on vendor.

 

[BTLSHP]

Yea, it's one of those items folks don't think about. I always keep a new spare in the truck and the existing one is strain relieved.
90982-08264 about $15-$20 depending on vendor.

Ordered. So, with the next owner a sub-30 that makes her living in a small corner of the outdoor sports industry and is a professional rock climber the car will be going to some fairly remote areas from Denver. 70-90% of the drive will be interstate, but she will end up in places like Rifle, CO and Joe's Valley, UT. No heavy 4 wheeling, but crappy roads. She has AAA and many of her companions are mechanically capable (the co-owner of her company is an Audi repair guy.)

The fusible link seems like a logical "glove box" spare. I have a bag of any unique tools I acquired for the rehab plus pliers I liked and I am ordering some JIS screwdrivers. There is also the original stainless steel PHH pipe and a new hose segment with clamps and left over Gates Green stripe 5/8" & 1/2" hoses and clamps about 2' of each with a cutter. I will include a small set of rachets and a real lug wrench. She also gets chains all around.

I can't provide every "spare" but are there some obvious bits that should be added?

 

[jonheld]

I can't provide every "spare" but are there some obvious bits that should be added?

All the tools and parts in the world won't help if there's not a basic understanding of how systems work. The FSM and EWD are must haves.

 

[CruiseCruise]

Fusible links have a flameproof silicone jacket. You can not determine the condition with your eyeballs. They are prone to failure due to vibration and IMO should be replaced with every battery change. Since you disconnected the battery and now you said you've lost all power, my first thought is a battery clamp or the associated wires are loose or damaged.
That would be the low hanging fruit.

Would the car function just fine if my fusible link in anyway was bad or damaged? I drove it around last night and it seemed to work normal. I'm just confused as to why it was not fine one moment and then it was ok the next. Something seems to be a miss here.

 

[jonheld]

Would the car function just fine if my fusible link in anyway was bad or damaged? I drove it around last night and it seemed to work normal. I'm just confused as to why it was not fine one moment and then it was ok the next. Something seems to be a miss here.

Typically, no. But there have been folks who had their fusible links go intermittent.
We can speculate all day, but until you actually dive in, the problem will remain.

 

[Rollinns]

You said the motor mounts were replaced, did the shop leave a ground wire loose or disconnected?

It could be a ground from the motor to the battery, motor to the frame, battery to the frame, battery to the body.

It never hurts to clean the connection points of grounds and adding more grounds also never hurts. Poor grounds can cause a lot of weird electrical behavior

 

[Malleus]

All the tools and parts in the world won't help if there's not a basic understanding of how systems work. The FSM and EWD are must haves.

Especially for Audi mechanics

 

[Malleus]

Ordered. So, with the next owner a sub-30 that makes her living in a small corner of the outdoor sports industry and is a professional rock climber the car will be going to some fairly remote areas from Denver. 70-90% of the drive will be interstate, but she will end up in places like Rifle, CO and Joe's Valley, UT. No heavy 4 wheeling, but crappy roads. She has AAA and many of her companions are mechanically capable (the co-owner of her company is an Audi repair guy.)

The fusible link seems like a logical "glove box" spare. I have a bag of any unique tools I acquired for the rehab plus pliers I liked and I am ordering some JIS screwdrivers. There is also the original stainless steel PHH pipe and a new hose segment with clamps and left over Gates Green stripe 5/8" & 1/2" hoses and clamps about 2' of each with a cutter. I will include a small set of rachets and a real lug wrench. She also gets chains all around.

I can't provide every "spare" but are there some obvious bits that should be added?

Honestly, everything you need is already in the tool roll. Everything else is a convenience item.

Unless you're rock crawling, or spending time many miles away from civilization without cell service, if it runs in town, it'll run off road.

Apologies to the OP for the hijack.

 

[60 toy ota]

adding more grounds also never hurts

I see you've never had to battle with ground loops

 

[efjayatee]

Add an EFI fuse to your glove box too. And dont forget the ICM...its hardly mentioned.

 

[Brindleboxer]

Jonheld and Malleus have provided sound guidance, we now wait to see what you find. Use the available resources - download the FSM and EWD from the resource section and print out a no start troubleshooting guide from the pinned comments at the top of the forum (the later is just a good source document to have in the truck and is not necessarily needed in this situation). The symptoms you are describing would lead me to be checking the wiring harness near the EGR since this is a known area for electrical issues but this is in addition to foloowing the troubleshootig steps.

Here is how I approach issue: As a general rule, if something goes wrong (in anything that I do) I go back to the point before issues started and work from there. In your case you said the truck ran fine before the motor mount replacement so that is where I would start. I would double check everything that was touched at that time and verify the status of that component. Eliminate as much as possible and then work from there.

 

[CruiseCruise]

Jonheld and Malleus have provided sound guidance, we now wait to see what you find. Use the available resources - download the FSM and EWD from the resource section and print out a no start troubleshooting guide from the pinned comments at the top of the forum (the later is just a good source document to have in the truck and is not necessarily needed in this situation). The symptoms you are describing would lead me to be checking the wiring harness near the EGR since this is a known area for electrical issues but this is in addition to foloowing the troubleshootig steps.

Here is how I approach issue: As a general rule, if something goes wrong (in anything that I do) I go back to the point before issues started and work from there. In your case you said the truck ran fine before the motor mount replacement so that is where I would start. I would double check everything that was touched at that time and verify the status of that component. Eliminate as much as possible and then work from there.

Great Advice, I really appreciate it. I'll take a real good look over the weekend and go over anything that I may have missed. I'll check for loose connections and the condition of the wire harness near the EGR....I know I heat wrapped that area but still worth a check. I'm still not discounting the TPS connector wiring job that I did since it was the first time ever doing that sort of work.

 

[CruiseCruise]

I should also mention that I have a Noco Genius 1 (1 amp) battery maintainer on the vehicle when not in use which is most of the time since I don't drive this car too often. I'm not sure if that has anything to do with draining the battery or causing electrical issues.